The ASME A13.1 standard provides a system to identify hazardous materials transported in above-ground piping systems, as well potential hazards if the contents were released into the environment. It's commonly used in industrial and power plants, but is also recommended for use in commercial and institutional buildings and those used for public assembly. Pipe labels can be invaluable in an emergency situation, and will also help you comply with A13.1 standards.

Label Placement Labels should be positioned on pipes so they can be easily read. Labels are required at the following locations:

Near valves and flanges

Where direction changes

On both sides of walls or floors the pipe passes through

At regular intervals on straight runs, spaced for easy identification

Label ContentPipe marking labels must effectively communicate the contents of pipes and give additional detail of any special hazards, such as pressures or extreme temperatures. Pipe labels should indicate both the content of the pipe and its direction of flow. Arrows at one or both ends indicate flow; content is indicated by text and by a standard color scheme. If contents can flow both directions, arrows in both directions shall be displayed.

Label Color The current version of the ANSI / ASME code uses a color scheme with six standard color combinations and four user-defined combinations, based on the contents of the pipe. In general, the most hazardous feature of the contents should determine the color used. ANSI Z535.1 specifies exact safety colors for pipe labels.

Previous editions of the pipe-labeling code used a four-color scheme. The 2007 code applies only to new facilities; new labels in existing facilities should conform to the label scheme already in use to avoid confusion.

Note: This chart is presented for reference use only.
For complete specifications, consult the ASME A13.1-2007 Standard.